Radiation-cured microstructures have been described by Jacobsen et al. in “Compression behavior of micro-scale truss structures formed from self-propagating polymer waveguides”, Acta Materialia 55, (2007) 6724-6733, the entire disclosure of which is hereby incorporated herein by reference. One method and system of creating polymer materials with ordered microtruss structures is disclosed by Jacobsen in U.S. Pat. No. 7,382,959, the entire disclosure of which is hereby incorporated herein by reference. The system includes at least one collimated light source selected to produce a collimated light beam; a reservoir having a photo-monomer adapted to polymerize by the collimated light beam; and a mask having at least one aperture and positioned between the at least one collimated light source and the reservoir. The at least one aperture is adapted to guide a portion of the collimated light beam into the photo-monomer to form the at least one polymer waveguide through a portion of a volume of the photo-monomer. Microtruss materials produced by the method and system are further disclosed by Jacobsen in U.S. patent application Ser. No. 11/801,908, the entire disclosure of which is hereby incorporated herein by reference. A polymer material that is exposed to radiation and results in a self-focusing or self-trapping of light by formation of polymer waveguides is also described by Kewitsch et al. in U.S. Pat. No. 6,274,288, the entire disclosure of which is hereby incorporated herein by reference.
Products formed by bilayer resist processes have also been described, for example, by Orvek et al. in U.S. Pat. No. 4,770,739, the entire disclosure of which is hereby incorporated herein by reference. A first resist material sensitive to near UV or violet light is deposited over the top surface of a body. A second resist material sensitive to deep UV light is deposited over the first resist material. The second resist material is exposed to patterned illumination of deep UV light, and then exposed areas removed. The first resist material is illuminated by a flood or blanket exposure of near UV or violet light. The bilayer resist product is thereby formed.
Further known methods for fabricating microstructures include rapid prototyping technology, such as stereolithography, fused deposition modeling, and LIGA (a German acronym for Lithography, Electroplating, and Molding). A particular rapid prototyping technology for manufacturing microstructures is known as electrochemical fabrication, for example, EFAB™ developed by Microfabrica Inc. located in Van Nuys, Calif. The electrochemical fabrication process typically begins by depositing a sacrificial material onto a blank substrate in a desired pattern. The sacrificial material supports the microstructure, like scaffolding, during the fabrication process. A structural material is then deposited onto the sacrificial material. The sacrificial and structural materials are then precisely planarized, and the process repeated until the microstructure is fully assembled. The sacrificial material is ultimately removed, for example, by a highly selective etching procedure to leave the completed microstructure formed from the structural material. The use of electrochemical fabrication facilitates the manufacturing of microstructures with an extraordinary level of geometrical complexity, including the ability to create assemblies out of separate, independently-formed components. However, electrochemical fabrication and other conventional rapid prototyping methods are undesirably expensive and time consuming, particularly for applications such as automotive fuel cells.
There is a continuing need for a method for fabricating radiation-cured structures that is less expensive and time consuming in comparison to conventional rapid-prototyping methods. Desirably, the method facilitates the cost-effective formation of radiation-cured components for fuel cell and other applications.